High throughput extended incremental coefficient-lookahead filters based adaptive decision feedback equalizer

A novel time domain adaptive decision feedback equalizer (ADFE) architecture for a multi-gigabit 2-PAM wireline communication systems is proposed. The maximum throughput rates of traditional ADFEs are limited due to the loops in the circuits. We propose to do lookahead in coefficients instead of data to break the throughput rate limitation since it is less sensitive to tap number of feedback filter. To reduce hardware area, combination formulas for incremental coefficient-lookahead filters are proposed. The feedback loops of data equalization are transferred to the Extended Circuit which is a loop-free circuit. Therefore, approximations for slicer outputs are avoided and the parallelism factor can be small after fully pipelining. Besides, multipliers in a lookahead circuit except Extended Circuit are replaced with multiplexers. From the simulation results of a 10Gbps multi-mode fiber system, the hardware complexities of data-lookahead and the previously designed coefficient-lookahead ADFE are respectively 4.1 and 1.9 times the equivalent gate count of the proposed design which has only 0.3dB SNR degradation than traditional ADFE.